A broad-based index, the BSE-100 was formerly known as the BSE National index. This Index has 1983-84 as the base year and was launched in 1989. In line with the shift of the BSE Indices to the globally accepted Free-Float methodology, BSE-100 was shifted to Free-Float methodology effective from April 5, 2004. The method of computation of Free-Float index and determination of free-float factors is similar to the methodology for SENSEX.

Base YearThe financial year 1983-84 has been chosen as the base year. The price stability during that year and proximity to the index series were the main consideration for choice of 1983-84 as the base year. The base value was fixed at 100 points.

Dollex-100BSE also calculates a dollar-linked version of SENSEX and historical values of this index are available since its inception. (For more details click 'Dollex series of BSE indices')

Source : BSE

Calculation Methodology

Scrip selection criteria

The general guidelines for selection of constituents in BSE-100 are as follows:

Equities of companies listed on Bombay Stock Exchange Ltd. (excluding companies classified in Z group, listed mutual funds, scrips suspended on the last day of the month prior to review date, scrips objected by the Surveillance department of the Exchange and those that are traded under permitted category) shall be considered eligible.

Listing History: The scrip should have a listing history of at least 3 months at BSE. An exception may be granted to one month, if the average free-float market capitalization of a newly listed company ranks in the top 10 of all companies listed at BSE. In the event that a company is listed on account of a merger / demerger / amalgamation, a minimum listing history is not required.

The scrip should have been traded on 95% of the trading days in the last three months. Exceptions can be made for extreme reasons like scrip suspension etc

From the list of constituents selected through Steps 1-3, the top 150 companies based on free-float market capitalisation (avg. 3 months) are selected as well as any additional companies that are in the top 150 based on full market capitalization (avg. 3 months).

The filtered list of constituents selected through Step 4 (which can be greater than 150 companies) is then ranked on absolute turnover (avg. 3 months).

Any company in the filtered, sorted list created in Step 6 that has Cumulative Turnover of >99%, are excluded

The remaining companies are then sorted based on whether they are an existing member of the BSE-100 constituents and then on free-float market capitalization.

Industry/Sector Representation: Scrip selection will generally attempt to maintain index sectoral weights that are broadly in-line with the overall market.

Track Record: In the opinion of the BSE Index Committee, all companies included within the index should have an acceptable track record.